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Fam. 3. Pliocidae. — The true Seals have no external ears,
and the nostrils are quite dorsal in position as in other aquatic
animals, such as the Crocodile. There is obviously an approach
to the conditions characteristic of the Whales. The hind-limbs
are useless for locomotion on land. They are bound up with the
tail, and form functionally merely a part of the tail. In this
family there are, at any rate, eight genera.

Pkoco, and Halichoerus are not very wide apart from each
other. In both there are five well-developed claws on feet and
hands. They are British, and generally Arctic and temperate
in range. For some reason or other the late Dr. Grray placed
Hcdichocrus in the same sub-family with the Walrus ! Phoca is

Fio. 230.—Common Seal.   Pkoca, vitulina.    x£.   (From Parker and Harwell's Zoology.)
not only marine, but is found in the Caspian and in Lake
Baikal. Their existence in those inland seas is believed to be a
vestige of a former connexion with the sea. Halichoerus grypus
is a large seal 8 feet in length when full grown. Its colour is
yellowish grey, with darker grey spots and blotches. It is not
uncommon on the shores of our islands, particularly of the Hebrides
and Argyllshire. The commonest Seal is Phoca vitulina, not more
than 4 to 5 feet long, and of the same spotted coloration as the
last. This Seal has, however, a much wider distribution, being
Arctic as well as British, American, and North Pacific. A curious
fact about this Seal is that it is not impatient of fresh water;
not only will it ascend rivers, but it will live in inland lakes. It
is said to be especially sensitive to musical sounds. P. Mspida,
is British, but a rare visitor to our islands. It is essentially an
Arctic species. The Harp Seal, P. groerdandica,, is so called on
of a iharp-sfoaped black bar in the males, which starts at